1. Field of the Invention
This invention relates generally to a power cutter having a circular cutting blade which is adapted to be rotated by means of a motor, such as a small air-cooled two-stroke gasoline engine or an electric motor. In particular, the invention relates to a portable power cutter which is provided with a fan for sucking and removing dust generated in cutting concrete members, or the like, with the circular cutting blade.
2. The Prior Art
As described in Japanese Patent Publication H/7-14570, a portable power cutter provided with a fan for sucking and removing dust has been proposed or put into practical use. Namely, this conventional portable power cutter includes a main body provided with a motor, a circular cutting blade which is adapted to be rotated by the motor, a safety cover disposed on and covering both sides of an edge portion of the cutting blade so as to form a dust-discharging passageway, and a fan which is attached to the safety cover for sucking dust generated during cutting work using the circular cutting blade and removing the dust through the dust-discharging passage. A barrier wall is attached to the safety cover so as to substantially intercept the dust-discharging passageway, and a dust-sucking port for the fan is disposed in front of the barrier wall as viewed in the rotational direction of the cutting blade.
However, this conventional power cutter is subject to the following problem. Namely, since the aforementioned barrier wall is mounted so as to intercept the dust-discharging passageway as mentioned above, the barrier wall is required not only to be disposed over the outer periphery of the edge of the cutting blade but also extend to both sides of the edge portion of the cutting blade. In this case, a predetermined clearance must be maintained between the cutting blade and the portions of the barrier that extend on the sides of cutting edge portion. In other words, the extended portions of the barrier which are disposed on the sides of the cutting edge portion must be formed to have a slit-shaped opening having a predetermined width so as to allow the cutting blade to rotate therein without contact such extended portions.
However, if such a slit-shaped opening is formed in the barrier, a gap is inevitably formed between the cutting blade and the extended portions of the barrier. Therefore, the dust generated in cutting concrete members or the like inevitably leaks out through the gap toward the rear side of the cutting blade. Thus, a portion of the dust is discharged directly from the safety cover through the gap formed between the cutting blade and the extended portions of the barrier without being sucked through the dust-sucking port of the fan.